Production of carbon disulphide from hydrocarbons

ABSTRACT

A method for continuously producing CS2 by reacting sulphur in the gas phase with an unsaturated aliphatic hydrocarbon, such a propylene, in sulphurating apparatus in which the sulphur circulates the hydrocarbon being injected into the apparatus at at least two points and then condensing and recovering the CS2 therefrom. The sulphurating apparatus may include a reactor in addition to a coil within a furnace, and one of the points of injection can be to the reactor.

United States Patent Gerin et al.

[451 Oct. 17,1972

PRODUCTION OF CARBON DISULPHIDE FROM HYDROCARBONS Inventors: Paul Gerin,Clair du Rhone; Lucien Louat, Lyon; Jean-Pierre Quillet, les Roches deCondrieu, all of France Assignee: Progil, Paris, France Filed: March 19,1969 Appl. No.: 808,598

Foreign Application Priority Data March 26, 1968 France ..68145513 US.Cl ..423/443, 23/277 Int. Cl. .....C0lb 31/26 Field of Search ..23/277,284, 206

References Cited UNITED STATES PATENTS 6/1951 Marisic ..23/206 X 2/1954Folkins et al. ..23/206 2,989,380 6/1961 Weiss et al ..23/277 3,250,5955/1966 Olsen ..23/206 3,436,181 4/1969 Berthoux et al. ..23/2062,971,969 2/1961 Lobo ..23/252 X FOREIGN PATENTS OR APPLICATIONS 620,3153/1949 Great Britain ..23/206 Primary Examiner-Oscar R. Vertiz AssistantExaminer-Charles B. Rodman Attorney-Browdy and Neimark [57] ABSTRACT Amethod for continuously producing CS by reacting sulphur in the gasphase with an unsaturated aliphatic hydrocarbon, such a propylene, insulphurating apparatus in which the sulphur circulates the hydrocarbonbeing injected into the apparatus at at least two points and thencondensing and recovering the CS I therefrom. The sulphurating apparatusmay include a reactor in addition to a coil within a furnace, and one ofthe points of injection can be to the reactor.

9 Claims, 1 Drawing Figure LIQUID SULPHU R CS AND/0R H 5 I TUBULAR cou.

GOO-750C SULPHURATING REACTOR 3 HYDROCARBON C HARGE PATENTEDnc-r 17 I972XXX 903-com zoo 52;

N N 0000702 m I mO\QZ mu KDImJDw D503 ATTORNEYS PRODUCTION OF CARBONDISULPHIDE FROM HYDROCARBONS The present invention relates to a novelmethod of reacting sulphur and a hydrocarbon charge, preferablyconsisting of unsaturated aliphatic hydrocarbons, for the production ofcarbon disulphide. The invention relates to a method wherein thereactants are introduced into conventional apparatus to yield very purecarbon disulphide in excellent yields by a continuous industrialoperation.

Applicants have previously described a process for the continuousproduction of CS by reacting sulphur with an olefin or a diolefin in theabsence of any catalytic system, at a temperature between 600 and 850C., with contact times of between 0.1 and 20 seconds. in this previousprocess, the sulphur, which is generally employed in an excess over thestoichiometrically necessary quantity, optionally diluted with CS and/orH 8, is preheated in a furnace at a temperature of at least 550 C. andthereafter continuously passed into a sulphurating reactor supplied withunsaturated hydrocarbon, which is optionally preheated. Aftersulphuration under the aforesaid chemical conditions, the gaseouseffluents are condensed and the unreacted sulphur and the uncondensedgases are separated from the Cs produced. (U. S. application Ser. No.605,555 filed Dec. 29, 1966, now US. Pat. No. 3,436,181.)

This method, wherein the unsaturated hydrocarbon employed as startingmaterial is directly introduced either into the sulphurating reactor orinto the sulphurpreheating furnace, makes it possible to obtainsubstantially quantitative rates of conversion of hydrocarbon to carbondisulphide, which has a purity of the order of 99.99 percent. However,it is not always satisfactory in industrial operation owing to thedifficulties inherent in the thermal control of the reaction.

It has now been found that it is possible by means of a new method ofintroducing the reactants into the sulphurating apparatus anddistributing them therein to control the progress of the reaction withprecision, especially from the thermal viewpoint, by controlling therespective proportions of sulphur, hydrocarbon, carbon disulphide andhydrogen sulphide. There is thereby obtained a rapid and completereaction.

The novel process according to the present invention consists ineffecting at least two injections of unsaturated hydrocarbon atdifferent points into the sulphurating apparatus in which the hotsulphur circulates.

By sulphurating apparatus is meant the apparatus, already known per se,in which the supply of heat necessary for the reaction, and thesulphurating reaction itself take place. This apparatus precedes thebattery of units in which the conventional operations involvingcondensation of the gaseous effluents, absorption and desorptiontreatments and distillation of the CS take place. Such apparatus mayconsist, for example, of a tubular coil disposed inside a furnace, towhich there may be attached through pipes one or more reactorscontaining packing masses and optionally a catalytic system, in whichthe sulphurating reaction is completed.

By reaction volume is to be understood the volume of apparatus, as seenin the downstream direction, between the first introduction ofhydrocarbon charge into the sulphurating apparatus and the end of thisapparatus.

Although the technique of successive injections of hydrocarbons may beemployed, in accordance with the invention, at any points of thesulphurating apparatus, for example in the tubular coil heated by afurnace and thereafter at the inlet of the aforesaid reactor orreactors, the preferred and particularly advantageous form of inventionconsists in introducing the charge of unsaturated hydrocarbons at atleast two points of the coil fed with sulphur, one of which points maybe situated in a single sulphurating reactor optionally provided afterthe furnace.

The new technique of injections at multiple points will be more readilyunderstood with reference to the diagram accompanying the presentdescription.

The F IGURE which is a diagram illustrating the principle of asulphurating apparatus according to the invention shows a tubular coil 1situated in a furnace (not shown) and having its outlet connected bythepipe 2, either to a sulphurating reactor 3 as at 2a, or to all theconventional apparatus for the treatment, recovery and purification ofthe effluents (not shown in the figure), as at 2b.

In practice, in the arrangement shown, the coil 1, heated attemperatures between 600 and 750 C., is supplied at its upper part,through the pipe, 4, with liquid sulphur preheated to a temperature ofabout l30l50 C. The sulphur of which the excess over theoretical isgenerally between 1 percent and 50 percent is optionally diluted, beforeentering the coil, with CS and/or H 8 which optionally are obtained fromrecycling fractions and are introduced through the pipe 5. Thehydrocarbon charge employed as starting material and arriving throughthe general pipe 6 is injected in accordance with feature of theinvention at a number of points in the sulphurating apparatus. Inaccordance with a first embodiment, the hydrocarbon charge is passed, atnormal temperature, only into the coil along the paths 7 and/or 8 at'atleast two of the points of the coil represented by the letters A, B, D,E and F.

In accordance with another embodiment, which constitutes a variant ofthe preceding one, the stream arriving through 6 is divided into 2fractions of variable volumes which are introduced on the one hand intothe coil through the pipe 7 or 8 and on the other hand through the pipe9 into the sulphurating reactor 3 which may be mounted after thefurnace. The introduction of the hydrocarbon stream into this reactor isindicated at the point C situated at the bottom of the apparatus, but itis obvious that this type of injection may be carried out at any otherpoint of the reactor. The gaseous effluents emanating either from thecoil 1 in accordance with the first mode of operation or from thereactor 3 in the case of the variant are passed through the pipe 2b intothe conventional apparatus for the well known after-treatmentoperations, namely condensation of the sulphur, washing and absorptionand desorption of the gases, and distillation of the CS The chemicalconditions for-the sulphurating reaction are not a part of the presentinvention, since they have been described in the previously referred toprocess of applicants. However, it is important to emphasize that thetechnique of injection of the hydrocarbon charge at multiple pointsaffords the possibility of having at each point of injection aconsiderable excess of sulphur over the stoichiometry of the hydrocarbonfraction introduced. Now, ,it has been found that an excess of sulphurhas a particularly favorable effect on the inhibition of the formationof carbonaceous or tarry by-products. As. stated above, the sulphur maybe diluted before it is introduced into the furnace, notably with carbondisulphide,.preferably in vaporized form,-the ratio of S to CS generallybeing between 1:01 and 1:1.5 by weight. In the temperature range(600-750 C.) and the pressure range (1 to 10 bars) which are generallyadopted in accordance with the conventional processes, the residencetime may be very short, particularly when the coil constitutes the onlysulphurating apparatus, and preferably is between 1 and seconds.

The hourly space velocity (HSV) (ratio of the volume per hour of all thereactantsand diluents, if any, introduced into the sulphuratingapparatus and taken in gaseous form at 0 C. under 760 mm.l-lg.

the sulphur being considered in the form S to the reaction volume asdefined above) may vary within wide limits, for example between 50 and10,000. However, it has been found that the adoption of HSV values above1,000, for example between 1,200 and 5,000 h.' affords a possibility ofobtaining optimum critical conditions for the production of a very pureCS with a quantitative rate of conversion of the hydrocarbon charge.

The number of injections of the hydrocarbon charge into the sulphuratingapparatus according to the invention may be equal to or higher than twoand may reach four to five, the upper limit to be adopted beingdetermined only by technological requirements. Thus, for example, whenthis apparatus is limited to a single coil, the injections may becarried out at two, three or more of the points indicated by A, B, D, Eand F, these points being located at varying distances from the level atwhich the sulphur is introduced and being offset from one another. Whena sulphurating reactor is combined with the coil in accordance with thevariant of the process of the invention, the hydrocarbon charge isintroduced partly into the reactor, for example at the base (C), andpartly into the coil, at at least one point of the latter. 1n the latterembodiment, the reactor may optionally contain therein an inert solidmaterial, such as Raschig rings, for example, which act to favor thecontact between the gaseous reactants.

The unsaturated hydrocarbon charge employed as starting material mayconsist, as stated in the Applicants prior application, of olefins suchas ethylene, propylene, the butenes, thelight olefin cuts resulting frompetroleum cracking, diolefins such as butadiene, isoprene, etc., or ofmixtures of these products. These unsaturated hydrocarbons (thecomposition of which may vary from one injection to the other) may beemployed in the pure state or in the form of industrial products.

The new mode of injection at a plurality of points of the sulphuratingzone is not, however, limited to the case of the use of an unsaturatedhydrocarbon in major proportions in a hydrocarbon charge, but thetechnique of the invention may be usefully put into practice, with thesame advantages of flexibility of operation and ready control of thethermal profile of the sulphuration, when the hydrocarbon chargeconsists partly of saturated hydrocarbons and partly of unsaturatedhydrocarbons, whether they be introduced separately or in admixture atthe different levels of the suplhurating apparatus. Thus, for example,when mixed operation with a methane charge and a. propylene charge isdesired, the weight ratio of CH, to C l-I may be varied between thelimits of 120.1 and 1:10. When such starting materials are adopted, themethane may be introduced into the upper part of the coil (for examplebetween the pipe 4 and the point Am the accompanying figure) at one ormore points, and the propylene may be injected at at least two pointssituated downstreamof the injection of the methane, one of which pointsmay be at the base of a sulphurating reactor optionally associated withthe furnace/For example, Cl-l, can be introduced at the point G into thecoil in which the sulphur is already vaporized, while the propylene canbe injected either both at the points 13 (coil) and C (reactor) or at atleast two of the points A, B, E and F into the coil (absence of thereactor). In addition, in the case where the sulphurating zone com- Iprises a coil and a reactor, it may be advantageous. to

introduce into the reactor a catalytic mass which may consist, forexample, of silica gel. I

The following examples illustrate a number of modes of practicalapplication of the process according to the invention on anindustrialscale.

EXAMPLES 1 TO 4 Continuous production of carbon disulphide bysulphuration of industrial propylene (containing 6 percent of propane)was carried out in a sulphurating apparatus consisting of a single coilsuch as that shown at 1 in the accompanying figure (without the reactor3).

The liquid sulphur introduced into the coil through the pipe 4 at aninitial temperature of 140 C. was in a quantity exceeding by Y about 20percent the stoichiometrically necessary quantity. The propylene wasinjected at normal temperature into the coil by means of appropriatenozzles at the points A and B, at rates differing in each test. In theapparatus illustrated purely by way of example in the drawing, in whichthe furnace contains a tubular coil of a diameter of 20 mm., consistingof corrosion-resistant metal, the points A and B were situated at 42meters and 21 meters respectively from the outlet of the furnace, thetotal length of the coil being meters. 7

Under the reaction conditions summarized in the following table and athourly space velocities between 1,820 and 2,580, a liquid titrating morethan 99.9 percent of CS was obtained after separation of the excess ofsulphur and the condensation of the gaseous effluent. The rate ofconversion of propylene to CS was substantially quantitative.

EXAMPLE 5 There were continuously introduced into the coil, per hour, atthe inlet (through 4):

66 kg. of sulphur preheated at 140C. (i.e. a total The temperature ofthe furnace. was maintained between 650 and 680 C. The pressure at theinlet of the coil was in the neighborhood of 4 bars absolute and of theorder of 3.5 bars in the reaction zone. The hourly space velocity was ofthe order of 2,000 h.. After operation for 120 hours, without anyobstruction of the pipes occurring at any time, quantitative CS yieldswere obtained which titrated, before rectification, only 150 p.p.m.(parts per million) of benzene and 100 p.p.m. of thiophen. The ratio ofcarbon to excess of sulphur was less than 0.02 percent by weight.

EXAMPLES 6 TO 8 Continuous operations for the sulphuration of propylenewere carried out in a sulphurating apparatus comprising in this case acoil of the same type as that of Examples 1 to 4 and a reactor packedwith Raschig IlI'lgS.

The sulphur, of which the total excess was of the order of 20 percent,was introduced through 4 at the inlet of the coil at a temperature of150 C., optionally after having been diluted with a fraction of CSemanating from recycling of the production (pipe 5).

As hydrocarbon charge, non-preheated propylene was injected both intothe coil at the level of the point B and into the reactor at the levelof the base (C). The hourly space velocity varied between 200 and 600h'.

The other reaction conditions and the results obtained are summarized inthe following table:

The rate of conversion of propylene to CS was in the neighborhood of 99percent.

The percentage (by weight) of carbon in the sulphur varied between 0.1percent and 0.5 percent in the three experiments.

EXAMPLES 9 TO 11 Operations for the continuous manufacture of carbondisulphide by simultaneous sulphuration of natural gas containing 96percent. of methane and industrial propylene (containing 8 percent ofpropane) were carried out in the sulphurating apparatus of Examples 1 to4 (coil 1, without the reactor 3).

The liquid sulphur was introduced through the pipe 4 at an initialtemperature of 140 C.

The hydrocarbon charge at ambient temperature was injected as follows:

Example 9 mixed methane and propylene at B, E and F Example 10: methaneat G, propylene at A, E, F

Example 1 1: methane at G, propylene at B and F.

The other reaction conditions are summarized in the following table:

The rate of conversion of the propylene was substantially quantitative,while that of the methane varied between 98 percent and percent in thethree different experiments. The purity of CS obtained was similar tothat of the products obtained in the preceding examples.

What is claimed is:

1. In a process for the continuous production of carbon disulfide byreacting sulfur in the vapor phase with an unsaturated aliphatichydrocarbon in a sulfurating apparatus through which the sulfur ispassed continuously entering at one end and exiting at the other end andin which the sulfur and the hydrocarbon are contacted at temperaturesbetween about 660 C. and about 750 C. during a residence time betweenabout 0.1 and about 20 seconds, the improvement which comprisesintroducing the hydrocarbon reactant at more than one inlet point insaid sulfurating apparatus, said inlet point s being spaced successivelyaway from the point of introduction of said sulfur, said points ofintroduction and said rate of introduction of said hydrocarbon reactantbeing controlled so as to maintain a stoichiometric excess of sulfurover hydrocarbon at each point of introduction thereof.

2. A process according to claim 1 wherein the points in the saidsulphurating apparatus wherein the hydrocarbon charge is injected aredisposed entirely within a furnace and the gaseous effluents areimmediately treated for the recovery of the carbon disulphide.

3. A process according to claim 1, wherein the sulphurating apparatusincludes a portion disposed within a furnace and a reactor disposedafter the furnace and wherein at least one of the points of injection ofhydrocarbon charge is into said reactor.

4. A process according to claim 1 wherein the sulphur is introduced intothe sulphurating apparatus in liquid form at a temperature of about '150C., wherein the sulphurating apparatus is heated between 600 and 750 C.under a pressure of l to 10 bars before reacting with the hydrocarbon,the hourly space velocity of the reactants being greater than 1,000hours.

8. A process according to claim 7 wherein the hydrocarbon chargecomprises methane and propylene separately introduced into thesulphurating apparatus in CH C l-l ratios of between 1:0.1 and 1:10 byweight.

9. A process according to claim 1 wherein the hydrocarbon isselectedfrom the group consisting of an olefin and a diolefin.

2. A process according to claim 1 wherein the points in the saidsulphurating apparatus wherein the hydrocarbon charge is injected aredisposed entirely within a furnace and the gaseous effluents areimmediately treated for the recovery of the carbon disulphide.
 3. Aprocess according to claim 1, wherein the sulphurating apparatusincludes a portion disposed within a furnace and a reactor disposedafter the furnace and wherein at least one of the points of injection ofhydrocarbon charge is into said reactor.
 4. A process according to claim1 wherein the sulphur is introduced into the sulphurating apparatus inliquid form at a temperature of about 130*-150* C., wherein thesulphurating apparatus is heated between 600* and 750* C. under apressure of 1 to 10 bars before reacting with the hydrocarbon, thehourly space velocity of the reactants being greater than 1,000 hours 1.5. A process according to claim 1 wherein more than one hydrocarbon isinjected in admixture at each injection point.
 6. A process according toclaim 1 wherein more than one hydrocarbon is injected, each hydrocarbonbeing injected at a separate point.
 7. A process according to claim 1wherein the hydrocarbon charge comprises an unsaturated aliphatichydrocarbon and a saturated aliphatic hydrocarbon.
 8. A processaccording to claim 7 wherein the hydrocarbon charge comprises methaneand propylene separately introduced into the sulphurating apparatus inCH4: C3H6 ratios of between 1:0.1 and 1:10 by weight.
 9. A processaccording to claim 1 wherein the hydrocarbon is selected from the groupconsisting of an olefin and a diolefin.